Golf balls have a variety of constructions. Solid golf balls include one-piece, two-piece (i.e., solid core and a cover), and multi-layer (i.e., solid core of a center and one or more layers and a cover of one or more layers) golf balls. Wound golf balls typically include a solid, hollow, or fluid-filled center, surrounded by a tensioned elastomeric material, and a cover. While solid golf balls now dominate the marketplace because of their distance, lower cost, and durability, manufacturers are constantly trying to improve the “feel” of solid balls in an attempt to make it more like that associated with a wound construction.
By the materials used for golf ball construction, manufacturers can vary a wide range of playing characteristics, such as compression, velocity, “feel,” and spin, each of which can be optimized for various playing abilities. In particular, a variety of core and cover layer(s) constructions and compositions have been investigated, such as polymeric compositions and blends, including polybutadiene rubbers, polyurethanes, and ionomers. These ‘conventional’ materials, however, have inherent limitations in their properties.
It is now believed that blending nano-materials with conventional materials can improve the properties of the virgin material. It is also believed that forming golf ball layers with conventional materials in ‘nano’ sizes can provide improved properties compared to that of the same ‘larger’ material. The properties that can be improved include, but are not limited to, density, dimensional stability, stiffness, abrasion resistance, moisture transmission, and resiliency. Nanomaterials are unique because of their size and shape, and because they can be selectively modified by chemical or other sources at an atomic or molecular level. These nanomaterials, therefore, provide novel and sometimes unusual material properties (even at lower loading levels), such as increased modulus (in some cases even lower hardness), elongation at break, optical property, barrier to moisture, abrasion resistance, low hysteresis, and surface appearance, especially compared to identical materials of conventional (larger) size. These unique properties may be utilized for golf ball construction in manners previously not available.
One property in particular is important to golf ball construction—water vapor transmission rate (WVTR). Many conventional golf ball materials have elevated WVTR, allowing other golf ball materials to be degraded. One example is polyurethane, which can allow water vapor to diffuse into the polybutadiene core, causing a degradation of core velocity over time. There remains a need, therefore, to develop ways to decrease the WVTR, preferably without having to add an extra layer to the golf ball, without the layer inhibiting desirable golf ball properties. It is believed that the incorporation of nano-sized materials, in particular those that can provide a tortuous path through which water transmission is inhibited, will accomplish this endeavor.